1. Technical Field
The present invention relates to a support device such as is used in mobile lifting machines, in particular in vehicle cranes, in order to support them during operation. The present invention also relates to a mobile lifting machine, in particular a vehicle crane, comprising at least one such support device.
2. Background Information
Modern mobile cranes are used for lifting increasingly heavier loads to ever greater heights. The demand for using an efficient mobile crane which exhibits as low an inherent weight as possible, in order to reduce logistical costs, is increasing in the same way. A particular aim is to provide a mobile crane which exhibits as high a bearing load as possible on as few axles as possible, without exceeding the permissible axial loads. This has a favourable effect on the maneuverability of the mobile crane during transport on the one hand, and a lowering effect on the overall costs of the crane on the other. This stated object can also be transposed, unchanged, to other mobile lifting machines, for example movable working platforms or hydraulic rescue vehicles, which are supported by means of support devices during operation.
Such support devices consist substantially of a carrier support which can be extended or pivoted out of the vehicle chassis, and a support cylinder which is arranged in the region of the end of the carrier support pointing away from the vehicle chassis. The support cylinder in turn comprises a hydraulic cylinder and a piston rod which can be extended out of the hydraulic cylinder. In order to support the lifting machine, the piston rod is extended out of the carrier support, such that the lifting machine comprising a plurality of support devices is ultimately raised together with the carrier supports. Due to the design, the carrier supports are deformed during the support procedure by the application of force by the support cylinders. The resultant sagging at the outer end of the carrier support generates a transverse force that causes the piston rod to be deformed. The transverse force has to be accommodated by the piston rod as an additional load, which increases the calculated total force that has to be accommodated by the piston rod and taken into account when designing the piston rod.